Removal of oil from refrigerating systems



March 7, 1939.

"8. DE H. MILLE R 2,149,358 REMOVAL OF 011.: FROM REFRIGERATING SYSTEMS Filed NOV. 6, 1937 3 11 o COMPRESSOR J? m CH. CONDENSER RLFRIGERANT CONDENSER v 4- .14 h 2 .15 i: '--$aap;

l: I 60 2'; =6 Q? .50 40 EVAPDRATOR Z? i INVENTOR firmDejlfizwfl/w'der ATTORNEYS Patented Ma. 7, 1939 g 2,149,358

UNITED STATES PATENT OFF-ICE REMOVAL OF OIL FROM REFRIGERATING o SYSTEMS,

Bruce De Haven Miller, Louisville, Ky., assignmto The Girdler Corporation, Louisville, Ky a corporation of Delaware Application November 6, 1937, Serial No. 173,151 7 Claims. (01. 2-115) 1 This invention relates to a means for removing perature, and a certain amount 01 the lubricating oil from the volatile refrigerant circulated in 9. oil used in the compressor often mixes with the rating this extraneous oil from the useful refrigand the other cooled to a temperature at which provision of a simple and effective means for retype using cold water or o h r emperature lower- .serves to remove additional oil from the refrigdenser. After condensin th il from he resuch a manner in the refrigerating system that from the condenser i3 through pipe l4 into a the entire supply of refrigerant is compelled to filter l5 and discharged beneath the surface of P ss hrough the filter at all times. a liquid oil bath l6 maintained in the filter at Another object is to provide an eflective 011 all times. In order to insure a continuous and refrigerant therethrough. I! with the lowest point in the condenser so that Another-object is to provide the refrigerating c ndensed oilcannot accumulate in the condenser system with an oil filter means constructed in or be removed Separately therefromsuch a manner that oil may be removed without In lieu of the practice of prior oil removal 91 8 of any refrigerant held in solution with such means wherein the liquefied oil is removed sepa- Other objects and advantages of the invention advisable to prevent any stagnant pool of oil will become more apparent when considered in from forming in such condenser and contemplate connection with the accompanying drawing in so arranging the entrance oi pipe l2 into and which the exit of pipe I! from the condenser in such a The refrigerating system shown in Fig. 1 is an passes through pipe 20 into the main condenser other refrigerant vapor entering through pipe ll. liquefied under the necessary operating pressure. The gas may be compressed to or 200 pounds In so passing through the filter I 5 as described per square inch, and acquire a rather high temmore particularly hereafter, the gas is freed from I at which oil will condense, will merely bubble through provided with a drain pipe condenser 2| then passes through pipe 22 to any desired evaporator 23 and after fulfilling its refrigerating function passes in a gaseous state back into return line H at reduced pressure.

The improved filter means, shown in greater detail in Fig. 2, has the inlet pipe l4 carrying the refrigerant gas and liquid oil drops terminating at a substantial distance below the surface S of the oil bath l6. A screen 30 is disposed around the end of the pipe l4 and serves to hold an additional filter medium 3|, such as steel wool or the like, contained in the upper portion of the filter I5.

By means of the construction thus provided and particularly by means of the location of this construction in series with .the preliminary condenser l3 and the main condenser 2| of the refrigerating cycle, the following operation of oil removal will occur.

After the refrigerant gas enters pipe l4 at a temperature lower than that at which oil will condense under existing conditions, the oil drops swept along with this gas will remain in liquid state. In passing into contact with the oil bath l6, which too is at a temperature lower than that the refrigerant gas this liquid without taking up any oil vapor. The drops of oilentering with the gas have a mutual attraction for the similar oil in bah l6 and tend to agglomerate with such oil bath. Since the velocity of the refrigerant gas drops as it leaves the end of pipe l4, it will bubble through bathlB at low speed and will not mechanically sweep the oil out of the filter through pipe 20. To prevent any oil droplets from being carried out with the gas, a loosely packed barrier 3|, which may comprise steel wool or the like is provided. As will be apparent the bath I8 and the packing of steel wool do not provide any appreciable resistance to the flow of the gas and thus do not impose any additional load on compressor II]. In order to remove the thus recovered oil from the system, I provide the filter with a draw oif vessel 40 attached thereto by means of pipe 4| having any suitable valve 42. This valve may, if desired, be operated automatically by a float control mechanism (not shown) or maybe operated manually; Fromthe top of vessel 40 extends a pipe 43 controlled by a valve 44 and leading back into the intake side of compressor Ill. The lower portion of vessel 40 is 45 controlled by a valve 46 through which the recovered oil may be drawn off.

To aid in determining when the valve 46 should be operated, any su'table gauge 41 may be provided. As will be noted the interconnecting pipe 41 enters filter l5 at the upper surface S of the oil bath l6 and valve 42 is customarily maintained inopen position while v I ves 44 and 46 are-maintainedin closed position. As a consequence, after the liquid oil drops removed from the refrigerant raise the level of oil bath l6, this oil flows into draw off vessel 40 and forms a bath 48 therein.

A certain amount of refrigerant gas will be contained in the vessel 4|labove the surface of the oil, and since the system is maintained under high pressure it is likely that some of the refrigerant may actually be in solution in such oil. In order to avoid loss of any refrigerant, the following steps may be followed in drawing off oil from the vessel 40. Valve 42 is first closed and valve 44 gradually opened. As valve 44 is opened the suction of compressor I0 is exerted through off a portion but not necessarily all of Thevalve 46 is and the normal oil overflow from the filter permitted to continue.

pipe 43 and removes the entrapped gaseous refrigerant from the vessel 40 and due to the lowered pressure upon the bath 48 in such Vessel any refrigerant in solution will flash off and. be returned into the refrigerant cycle. If this results in a partial vacuum in the vessel 40, the valve 42 may be slightly opened after valve 44 is closed and enough gas permitted to enter vessel 40 to raise the pressure very slightly above atmospheric. The valve 46 may then be opened to draw the oil. then closed, the valve 42 opened This draw off. of oil may be done at as frequent intervals as necessary and without in any way interrupting or interfering with the normal operation of the system.

For the purpose of introducing the original bath of oil l6 at the start of an installation or for draining it away when occasion demands, I

provide an outlet pipe 50 from the filter l5 controlled by a valve 5|.

temperature employed. Merely as an example, IV

have shown a pipe 60 taking the warm water from the'condenser l3 and leading to a coil in .the filter l5 above the plate 30. This pipe as well as the pipes supplying liquid to thetwo condensers may. be provided with thermostatically controlled valves.

' with the gas and collecting in the trap is very large so that frequent draining of the oil is necessary, I may operate the valve 42 by a float in the liquid in the chamber I5.

Having thus claim as new and desire to secure Patent is:

1. In a refrigeration system having oil vapor described my invention, what I by Letters mixed with the gaseous refrigerant under presi be found that a small densing point of the oil vapor but not to the condensing point of the refrigerant, an outlet from a lower portion of said condenser through which the entire mixture of refrigerant gas and condensed oil is delivered at a veloc'ty suflicient to prevent retention of films of condensed oil on the condenser surfaces and to prevent the formation of stagnant pools of oil in the condenser, whereby the movement of the materials under pressure will scour the condenser surfaces and sweep condensed oil therefrom, a second condenser for the gaseous refrigerant, and an oil trap between the two condensers.

2. In a refrigeration system having oil vapor mixed with the gaseous refrigerant under pressure, the combination of a condenser receiving the oil refrigerant mixture and adapted to lower the temperature of said mixture below the condensing point of the oil vapor but not to the condensing point of the refrigerant, an outlet from a lower portion of said condenser through which the entire mixture of cooled refrigerant gas an condensed oil is delivered at a velocity sufficient to prevent retention of films of condensed oil on the condenser surfaces and to prevent the formation of stagnant pools of oil in said condenser, a filter means for separating the condensed'oil from the gaseous refrigerant, and means for returning into the system. any refrigerant entrapped with said separated condensed oil.

3. Means for removing oil from refrigerating systems, including a condenser receiving a warm oil gaseous refrigerant mixture under pressure and serving to condense said oil while cooling but not condensing the refrigerant gas, a pressure vessel having a bath of oil therein, means delivering the entire mixed contents of the condenser below thev surface of said oil bath whereby the oil bath serves to agglomerate oil particles from said mixture and to filter oil from the gas, and

means for delivering the removed oil and the filtered gas separately from said pressure vessel.

4. A refrigerating system including a compressor for a volatile refrigerant, two condensers in series, means for cooling the first condenser to a temperature at which oil vapors from the compressor will condense but above the condensing temperature of the refrigerant under the pressure employed, means for cooling the second condenser to a temperature at which the refrigerant gas will liquefy, an oil collecting chamber between said condensers, and means for delivering the gaseous refrigerant and condensed oil from the first condenser. below the liquid level of the oil in said chamber. a

5. A refrigerating system including a compressor for a volatile refrigerant, two condensers in series, means for cooling the first condenser to a temperature at which oil vapors from the compressor will condense but above the condensing temperature of the refrigerant under the pressure employed, means for cooling the second condenser to a temperature at which the refrigerant gas will liquefy, an oil collecting chamber between said condensers, a perforated plate within said chamber below the normal oil level therein,

means for conducting gaseous refrigerant from the upper portion of said chamber to the second condenser.

6. A refrigerating system including a compressor for a volatile refrigerant, two condensers in series, means for cooling the first condenser to a temperature at which oil vapors from the com pressor will condense but above the condensing temperature of the refrigerant under the pressure employed, means for cooling the second condenser to a temperature at which the refrigerant gas will liquefy, an oil collecting chamber between said condensers, means for delivering the gaseous refrigerant and condensed oil from the first condenser below the liquid level: of the oil in said chamber, a second chamber, valve controlled connections between said chambers permitting oil to flow to the second chamber, a valve controlled drain from said second chamber, and a valve controlled connection between the upper portion of said second chamber and the intake of said compressor.

7. A refrigerating system including a compressor for a volatile refrigerant, two condensers in series, means for cooling the first condenser to a temperature at which oil vapors from the compressor will condense but above the condensing temperature of the refrigerant under the pressure employed, means for cooling the second condenser to a temperature at which the refrigerant gas will liquefy, an oil collecting chamber between said condensers, means for delivering the gaseous refrigerant and condensed oil from the first condenser below the liquid level of the oil in said chamber, a second chamber, valve controlled connections between uniform oil level in the first mentioned chamber, a valve controlled drain from said second chamber, and a valve controlled connection between the upper portion of said second chamber and the intake of said compressor.

BRUCE DE HAVEN MILLER. 

